Film-Tech Forum ARCHIVE: Exhaust Duct sources needed

This is topic Exhaust Duct sources needed in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005177

Posted by Barry Floyd (Member # 385) on 08-06-2003, 10:29 AM:

Our Xenex II Lamphouse has a 6" outlet on the top for the exhaust duct, and I need to find a source for the actual duct itself. I don't want to use standard "flex duct" like you use on HVAC stuff, but a flexible rigid metal duct.

What do you guys use, and where can I get some??

Posted by Ken Layton (Member # 133) on 08-06-2003, 10:36 AM:

You can get the flexible aluminum ducting at Home Depot.

Posted by Gordon Bachlund (Member # 124) on 08-06-2003, 06:16 PM:

And, if a Home Depot or Loews is not handy, McMaster-Carr and Granger are reliable sources and will accept phone and internet orders.

Posted by Phil Hill (Member # 371) on 08-06-2003, 07:07 PM:

I would use the least amount of flex duct as possible. Use straight rigid ducts as much as possible right down to within a few inches of the lamphouse.

The flex ducts severly restrict airflow and induce internal turbulance.

>>> Phil

Posted by Steve Guttag (Member # 268) on 08-06-2003, 08:10 PM:

I generally use flex for a minimum of 3-feet with celing line to lamphouse as typical.

Home Depot does have the "semi-rigid" duct. My preference is definately insulated though.

Steve

Posted by Chris Markiewicz (Member # 1415) on 08-06-2003, 09:26 PM:

I agree with everyone above. Another source for flexible metal ducting is a woodstove supply dealer. We have stainless flexible and rigid piping in my mom's house.

Posted by Bruce McGee (Member # 131) on 08-06-2003, 09:35 PM:

Any good heating supply house in the Nashville area will have rigid 6" duct pipe in 3', and 5' lengths. 6" elbow pipes are fully adjustable.

24ga metal is the best. It's used as flue pipe on furnaces, etc. 30ga is thin. It is used mostly in HVAC ductwork.

I agree with not using flex aluminum. Holds the air back!

Use self-tapping sheet metal screws when you attach the pipes and elbows together.

Posted by Greg Mueller (Member # 17) on 08-07-2003, 09:23 AM:

I went to Home Depot and got 6" rigid duct and then one piece of flex duct too. I mounted the rigid up in the ceiling between the rafters and went from that to the lamphouse with the flex. I got 2 inline helper fans from McMaster Carr for about $30 each and have them wired to a switch on the wall. Now the rigid pipe sucks and the lamphouse blows.

Posted by Barry Floyd (Member # 385) on 08-07-2003, 09:57 AM:

Would you guys suggest to get a 6" x 8" adapter, and run 8" all the way up to the exhaust fan or keep it 6" until I get to the fan?

One of the other drive-in owner's suggested I transition from 6" up to 8"???

I want to make this a clean as possible installation.

Posted by Greg Mueller (Member # 17) on 08-07-2003, 10:03 AM:

The bigger the pipe the less "wall turbulence". I guess size depends on how many kw you are running.

Posted by Andrew McCrea (Member # 674) on 08-07-2003, 10:30 AM:

I know a company called "Dundas Jafine" that makes ducts, adpaters, etc.

Check it out: http://www.dundasjafine.com

Andrew

Posted by John Pytlak (Member # 331) on 08-07-2003, 11:02 AM:

Welcome back to Film-Tech Andrew! (Hopefully older and wiser. [Wink]

)

Posted by Barry Floyd (Member # 385) on 08-07-2003, 11:11 AM:

Good to see you back Andrew.

I'm running 4kw... with a water cooled gate

Posted by Gordon McLeod (Member # 33) on 08-07-2003, 12:05 PM:

Every elbow every turn adds what is called static pressure to the system.
The size of the exhaust fan and the motor horsepower needs to based on the volume of air required to be moved at a given velocity and at what static pressure
I usually use a square duct from the fan to the ceiling area above the lamphouse and then a piece of flex straight down to the lamphouse
A bypass damper at the juntion of the flex and the duct will allow the contractor to balance the system for the desired airflow

Posted by Marc Jones (Member # 29) on 08-07-2003, 12:20 PM:

look at
http://www.mcmaster.com/
thanks

Posted by Steve Anderson (Member # 364) on 08-07-2003, 03:58 PM:

Barry,

Louis put in a new lamphouse in our small theater,he used a square duct from the fan to the ceiling area then a piece of flex straight down to the lamphouse. Booth has been cooler since the install.

So your at the stage of installing the booth equipment?
That's great! .... Let me know if you need any help.

Posted by Barry Floyd (Member # 385) on 08-07-2003, 04:37 PM:

Steve.... we're not installing equipment yet. Just trying to locate sources for last minute needs. The roof of the building just went on yesterday, and the interior has yet to be finished. We're not moving a thing in until we can lock down the building securely.

We're shooting for an August 22nd opening date... but I'm still waiting on lenses to show up. We'll probably be moving in the weekend of the 15-16-17th.

Posted by Steve Anderson (Member # 364) on 08-07-2003, 05:04 PM:

Keep up the good work! New scope lens at the Franklin-DI wow what a difference! Hope you survived the series of storms the last few weeks. I stopped by a couple of weeks ago ....nice fence! Drive-In looking really good!!

Posted by Gordon Bachlund (Member # 124) on 08-07-2003, 05:28 PM:

For a glimpse of the way some lamphouses were ducted in some of the theatres I worked in the 1950s and 60s, see "The Metro Theatre" pix dated 7/16 in "public additions" on the home page, except that most had a "pettycoat" type downdraft diverter at the end of the duct over the lamphouse vent, and, of course, a damper for balancing and controlling draft.

Posted by Andrew McCrea (Member # 674) on 08-07-2003, 11:43 PM:

So, Which would you guys suggest as the better idea?

The Metal Duct

The Flex Duct

Posted by Phil Hill (Member # 371) on 08-07-2003, 11:49 PM:

Andrew: See the above posts for the pros & cons...

>>> Phil

Posted by Adam Martin (Member # 641) on 08-08-2003, 12:51 AM:

Gordon briefly mentioned this earlier, but it's worth noting: Keep the changes in direction to a minimum. The straightest shot possible will draw more airflow by increasing the efficiency of the motor and reducing turbulence. Very important for higher-power lamps. And don't forget to seal the joints.

Posted by Barry Floyd (Member # 385) on 08-08-2003, 09:09 AM:

Looking over my choices, I might end up going with a 14" x 14" square duct, (Insulated duct-board) and then dropping an 8" flex from the ceiling to the lamp and then find a 6" x 8" reducing collar.

Posted by Ken Layton (Member # 133) on 08-08-2003, 09:25 AM:

Good idea, Barry. That 8" duct may come in handy if you upgrade to a bigger or different lamphouse. Most of the lamphouses in the 3,000 to 4,500 watt variety have 8" hole in the top of the lamphouse.

Posted by Phil Hill (Member # 371) on 08-08-2003, 09:27 AM:

Barry, also make sure you have a "rain loop" in the path so as not to allow any rain storms to get H2O into your lamphouse.

Oh, and bee hives! [Smile]

>>> Phil

Posted by Gordon Bachlund (Member # 124) on 08-08-2003, 10:15 AM:

Geez, Phil, now you've spoiled the surprise! [Wink]

Posted by Andrew McCrea (Member # 674) on 08-08-2003, 11:39 AM:

Barry, I think the idea of that big duct with the 8" drop down is a good idea.

In a multiplex, could you have, lets say, all 8 lamphouses hooked up to that big duct with the drop downs, and have one mega machine, or should each house have its own machine?

As to the straight down awnser, is the metal duct or the flex duct the one that should be used?

Thanks, Andrew

Posted by Barry Floyd (Member # 385) on 08-08-2003, 12:34 PM:

Phil suggested a "rain loop" in the duct line somewhere.

Would I need this even if the exhaust fan will be a side-wall mount? I'll be using a "downblast" fan with a "mushroom" looking hood over the top. The fan itself will be wall mounted directly under the overhanging eve of the building.

Since the 14" x 14" duct will be up above the ceiling, I could slope it up 4" - 6" on the far end, so if any rain did make it past the fan, it would all collect on the opposite end from the projector and lamphouse.

Posted by John Pytlak (Member # 331) on 08-08-2003, 01:04 PM:

Don't forget to screen the output of the vent to keep critters (birds, squirrels) and insects (bees, wasps, and hornets) out. And keep the screen clean so as not to obstruct the airflow.

Posted by Jack Ondracek (Member # 1466) on 08-08-2003, 01:13 PM:

quote:
In a multiplex, could you have, lets say, all 8 lamphouses hooked up to that big duct with the drop downs, and have one mega machine, or should each house have its own machine?

Sure... you can do it both ways. A couple of shopping centers around here use that single (master) blower concept.

Personally though, I wouldn't design a system that way if I had the option. That blower would represent a single failure point that could take down the whole operation.

We recently learned the value of separating systems when one of our power supplies spiked the main breaker feeding a load panel. Because each of our screens has its own breaker board, only the one screen went down.

Posted by Kris Brunton (Member # 432) on 08-09-2003, 11:52 AM:

I tend to prefer one exhast fan per machine, as Jack mentioned only one fan is a point of falure for the whole booth. - And they do fail!

I also inist to mechanical engineers to keep the design VERY simple. All you need in my opinion is a lighted switch in paralell with a 30 minute timer. I have seen some very overengineered systems that unfortunatly got ripped off the wall in favor of the switch and the timer.